The present invention relates to a plasma processing apparatus and a plasma processing method for processing a processed substance utilizing plasma produced by a plasma etching apparatus, a plasma chemical vapor deposition apparatus or the like.
In this specification, the term "aluminum material" means pure aluminum and aluminum alloys.
Since high corrosive gases such as chlorine gas and the like are used in a vacuum processing chamber of a plasma processing apparatus such as a plasma etching apparatus, a plasma chemical vapor deposition apparatus or the like, the vacuum processing chamber has been made of a highly corrosion resistant material such as stainless steel, quartz glass, aluminum oxide ceramic and so on. An apparatus of this kind is disclosed, for example, in Japanese Patent Application Laid-Open No.62-103379.
In a case of employing a stainless steel for a vacuum processing chamber of a plasma processing apparatus, the stainless steel itself releases its composite elements of Fe, Ni, Co and so on by impact of charged particles in a plasma. Therefore, in a semiconductor device manufacturing process, there has been a problem of heavy metal contamination.
On the other hand, the problem of heavy metal contamination can be solved by using a quartz glass cover, but the processing characteristic is sometimes changed because temperature of the quartz glass cover is increased over time by impact and thermal radiation of the plasma. In such a case, it is effective to heat or to cool the quartz glass cover using some means, but in most cases there are structural and technological difficulties because the quartz glass is exposed to vacuum and plasma in the plasma processing apparatus.
There is an aluminum material as a material which does not have the problem of heavy metal contamination and has better workability including heating or cooling. However, in this case, there is a problem in that the aluminum material does not have corrosion resistance against a gas plasma containing chlorine atoms or bromine atoms used in a plasma processing apparatus. For a countermeasure of the problem, a method is disclosed, for example, in Japanese Patent Application Laid-Open No.62-103379 where a highly corrosion resistant film made of Al203, AlC, TiN, TiC, AlN or the like is formed on the surface of an aluminum material structure through some means.
However, in a plasma processing apparatus using a gas containing fluorine atoms, no countermeasure has been taken against time-varying processing characteristic due to fluorination of the material itself composing the processing chamber.